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This invention relates to an antenna system comprising numerous radiation elements.
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An Active Electronically Scanned Array (AESA) is composed of numerous radiation elements. Due to the numerous radiation elements the AESA can be directed in a desired direction, by using a number of different frequencies of coherent radio energy that interfere constructively at certain angles in front of the antenna.
To achieve the desired effect, that the radio energy, from the individual radiation elements, interfere constructively the radiation elements must be positioned with an exact predetermined distance relative each other. Normally, each radiation element is mounted at circuit board carrier which then includes a number of radiation elements with Transmittal Receiver Modules (TRM), distribution network, power and logic. The radiation elements are mounted directly at the circuit board carrier or at a separate board which then can be mounted on the circuit board carrier. The high precision required in the mounting of the individual radiation elements relative each other, results in complex mounting solutions, and thereby high costs for the manufacturing of the mechanics, the mounting of the radiation elements and the handling of the all the involved parts.
The mounting solutions used so far in the AESA, are similar to the ones used for holding and supporting of circuit boards. With this background, the U.S. Pat. No. 4,477,135 is considered as closest prior art and discloses a attachment element for mounting and holding a printed circuit board onto a support panel, another printed circuit board or the like. The attachment element has a unitary flange extending outwardly from it; this unitary flange is used to attach the attachment element to a support panel or another printed circuit board, as by welding. To mount numerous radiation elements with the attachment element of U.S. Pat. No. 4,477,135 with the high precision needed for the use in a AESA would be very time consuming and expensive, since at least two unitary retainers has to be welded with high precision for each radiation element.
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OF THE INVENTION
Therefore the object of the present invention is to provide an antenna system, in which the radiation elements can be attached in a secure way and with a high precision at a low cost.
The antenna system according to this invention comprises numerous radiation elements, at least one circuit board carrier, at least one circuit board and at least one radiation element retainer device. Said radiation element retainer device comprising an attachment means, which attaches one radiation element to the radiation element retainer device such, that said radiation element can be electrically connected to the at least one circuit board which is arranged on the at least one circuit board carrier. The invention is characterised in, that the radiation element retainer device further comprising a main board on which the attaching means is located and that one radiation element retainer device comprising a plurality of attachment means, whereby said attachment means are integrally formed with the main board, such that the attachment means and the main board consists of one single piece of material. The attachment means and the main board together forms the radiation element retainer device.
Due to the presented inventive construction of the antenna system, with a radiation element retainer device, a plurality of radiation elements can be quickly and with high precision mounted and fixed to the main board. The position of the individual radiation elements, mounted on the radiation element retainer device, relative the neighbouring radiation element is fixed. Thereby, the needed accuracy in the positioning of the radiation elements relative each other is guaranteed and this, to low cost and in a fast mounting procedure. No additional positioning or fixing procedure (i.e. welding, screwing, etc.) is needed, when mounting of the radiation elements.
Obviously, there are numerous alternative ways to construct the single attachment means to achieve a fixation of the radiation element. This invention is not limited to one of them, rather does it include all attachment means suitable to be integrally constructed with the main board of the radiation element retainer device, such that the main board and the attachment elements consists of one single piece of material. One specific construction of the individual attachment elements is shown in the figures, several other constructions my though be suitable.
The attachment means of the radiation element retainer device positions the radiation elements in the X-, Y- and Z-direction, wherein the X-, Y- and Z-direction are perpendicular to each other. Thereby, the radiation elements are secured in all directions, such that they are positioned with low tolerances with a predetermined distance to each other. Further, the radiation elements are fixed by the attachment means such that they can stand disturbances which can occur in a rough surrounding, such as an aircraft flying in turbulence, or a ship in stormy water.
Further, the radiation element retainer device is fabricated as of a ductile and/or flexible material such as metal, a polymer, a carbon fibre or the like. Thereby can the attachment means be formed such that a snap-fit connection between the radiation element and the attachment means can be realised, where applicable. Whereby a corresponding snap fit means is formed on the radiation elements. Still, another possibility is that the radiation element retainer device is fabricated in a stiff material, and the radiation element is ductile and/or flexible, at least at the attachment points, such that a snap-fit between the two is possible.
In an embodiment of the invention, the radiation element retainer device is made out of a single piece of metal sheet. The profile of the attachment means can thereby be cut out from the metal sheet, such that they can be bended into the required position to receive the radiation element. The cutting and bending has to be done with high precision, because of the low tolerances for the distance between the radiation elements. Such a cutting method could be laser cutting or alternatively a high precision mechanical cutting or even punching method. Naturally, the bending of the material must also be done with corresponding high precision to achieve the desired low tolerances of the end product. A preferred materiel for the radiation element retainer device is thin steel, with high flexibility; a plastic material is also a possibility. Further materials which could be suitable are aluminium, aluminium alloy and other light weight metallic materials.
Alternatively, the radiation element retainer device can be made out of a polymeric material. The whole radiation element retainer device can thereby be injection moulded into the required form. Thereby, the required form of the attachment means and the main board is achieved immediately, without any need for extensive finishing treatments.
Further, the radiation element retainer device and the attachment means can alternatively be made out of carbon fibre.
Further, the circuit board carrier can be integrated with the radiation element retainer device, such that it is made out of the same piece of material (independent of the choice of material and manufacturing method of the radiation element retainer device). Thereby can another step in the production of the AESA be eliminated, since the radiation element retainer device, does not have to be placed and fixed to the carrier board.
Still further, independent of the choice of material and manufacturing method, the carrier board could alternatively be hollow. Whereby, a ventilation system and/or cooling fluid conduit can be arranged in the hollow interior of the carrier board.
For all embodiments of the radiation element retainer device, the attachment means are arranged in one row at radiation element retainer device, such that when the radiation elements are mounted on the main board, the radiation elements are arranged in a row. Further, the attachment means can be arranged in a plurality of rows on the radiation element retainer device and thereby create a matrix of attachment means. The position of one attachment means in one row can be equal to the corresponding attachment means in a neighbouring row. Alternatively, the position of the attachment means in one row can be displaced relative the corresponding attachment means in a neighbouring row, such that a triangular matrix is created. The more attachment means that can be arranged on one radiation element retainer device, i.e. number of radiation elements that can be mounted on the radiation element retainer device, the faster and easier can the mounting of the numerous radiation elements on one radiation element retainer device, in the AESA be done. Further, a high number of attachment means secures a correct distance between all the radiation elements mounted on that radiation element retainer device. Thereby are sources of errors which occur in the seams between two radiation element retainer devices minimized.
To adjust the radiation element retainer device to be fitted in different surroundings, i.e. a wing of an aircraft of in a spherical radome, etc, it is provided that that the radiation element retainer device is curved in one or two directions, such that radiation element retainer device has the form of a cylinder segment or sphere segment.
To realise that the distance between a radiation element mounted last in a row at the radiation element retainer device has a predetermined distance to a neighbouring radiation element mounted at a neighbouring radiation element retainer device, the radiation element retaining device has fitting means arranged at its edges. The fitting means are thereby arranged in such way, that two neighbouring radiation elements mounted in their respective attachment means, at two different neighbouring radiation retainer devices, are at a specific predetermined distance from each other. The predetermined distance is preferably the same distance as the distance between two radiation elements mounted in the same row at the same radiation element retainer device.
The inventive antenna system presented above secures that the numerous radiation elements are mounted at their respective position with the high tolerances needed. The mounting can be performed quickly and to a low cost.
BRIEF DESCRIPTION OF THE DRAWINGS
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FIG. 1 discloses a schematic view of a radiation element retainer device.
FIG. 2 discloses schematic close up view of the attachment means.
FIG. 3 discloses a piece of metal sheet with cut outs.
FIG. 4 discloses another schematic view of a radiation element retainer device with an integrally formed circuit board carrier.
FIG. 5 discloses a schematic view of a radiation element retainer device in which the attachment means are arranged in a matrix.
FIG. 6 discloses a schematic view of a radiation element retainer device with the attaching means arranged in a triangular matrix.
FIG. 7 discloses a schematic view of a radiation element retainer device which is bended in one direction.
FIG. 8 discloses a schematic view of a radiation element retainer device which is bended in two directions.
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OF THE DRAWINGS